All About the Wilwood Workhorse Mustang

Recovered in Ojai, California, this 1966 Ford Mustang was equipped with a 200ci six cylinder and automatic transmission. Though tired and sad looking, it was mostly solid. Once at Wilwood it was immediately stripped of everything that could be removed, sandblasted and primed, before the real work began. The Wilwood team made key modifications to match modern street driving demands, then upgraded everything for track and autocross duty. More than two years and countless man-hours later, the Workhorse Mustang was ready to roll.

When this tired old gelding arrived at Wilwood Engineering HQ in Camarillo, it was nothing to brag about. This 1966 Mustang T-code was about as basic as they come, with few factory options except for the C4 "Cruise-O-Matic" automatic transmission. There were tiny drum brakes all the way around, four lug wheels, and the base six cylinder which had once made 120hp.

We didn't feel at all bad about cutting this car up at all in order to make it go, stop, and turn better. 

But First... a Four Lug Brake Kit

Wilwood didn't just buy this car to build a fun to drive pony car to show off at events. This Mustang was first pressed into R&D duty for the Wilwood Forged Dynalite Pro Series Front Brake Kit for six cylinder cars retaining the stock four bolt wheels. It used to be that Mustang, Falcon, Ranchero, and Mercury Comet owners would upgrade to five-bolt hubs and disc brakes via readily available Ford parts in any junkyard. Wilwood kit 140-12535 allows you to upgrade your front brakes for safety in modern traffic, while fitting under 14-inch wheels and using a Ford manual or power brake master cylinder. 

The Wilwood Forged Dynapro Low-Profile Rear Kit with parking brake bring disc brakes to the rear as well. This kit features our Wilwood's hidden internal drum parking brake in the rotor, and fits behind the stock 14-inch, four-bolt wheels.

Start With a Clean Slate

Once the development team was done with the Mustang, it was disassembled to the point where it was nothing but the main shell. Anything that could be removed was, motor, transmission, suspension, brakes, interior, trim, glass, etc. The remains were loaded into the back of a truck and shipped off to Pacific Coast Powder Coating to be bead blasted down to the bare metal, and sprayed with a protective coat of primer.

Then it was time for the plasma cutters to come out, and things got really serious! In order to fit a modern Ford 5.0-liter Coyote engine, the Mustang's shock towers have to be taken out. But, since we were upgrading the front suspension to a full TCI pro touring tubular control arm setup, with coil overs, we weren't going to need them.

Inside the car we had more surgery to do. There was no way a Tremec T-56 Magnum six-speed transmission was going to fit in the tunnel sized for a three-speed. While the motor and interior were out, the firewall was measured and a set of brackets and pedals were created to bolt in with our brake and clutch master cylinders.

The Chassis and Frame

The Ford Mustang has always been a unibody car, without a separate frame, and the early 1960s design plus 50 years of age makes it about as rigid as a beer can. Combine the flexible body/frame with 1960s front end geometry and the vagueness of rear leaf springs, and we knew just bolting on wide sticky tires and big brakes wasn't the solution. Luckily, Total Cost Involved (TCI) has engineered a total package for these cars that stops just short of sliding a whole new car under the classic body.

The stock Mustang has an A-arm suspension with the springs riding on top of the upper arm, and held by towers which intrude into the engine bay. The TCI Mustang Pro Touring IFS eliminates the shock towers, covers the holes left from cutting them out, and strengthens the whole front of the car with weld in frame reinforcements and a new crossmember.

Then, TCI started with a new spindle and engineered a all new a-arm suspension with modern geometry and strength, held up by adjustable RideTech coil over shocks. The weld in crossmember is designed for more ground clearance, and a quick ration steering rack from a Fox Mustang, with practically zero bump steer. Because of all this new engineering, the Workhorse how has better Ackerman, a tighter turning radius, and steers more like a modern car.

The rear TCI Torque-Arm Suspension incorporates subframe connectors that stretch from alongside the transmission, back to where the the leaf springs used to be. Two new crossmembers are also installed, one in the front to locate the torque arm, and another above the differential to mount the coil overs. A pair of control arms work with the torque arm to locate the rear and control pinion angle, while an adjustable Panhard bar limits lateral motion.

All of these TCI rear components are connected to a Strange Engineering Ford nine-inch differential with full floating axles. Full floating axles are much more common on trucks and race cars than on street builds, but they have several advantages.

In a floating axle rear, the axle shaft itself only transmits power, with the rear end housing and wheel hub supporting it and holding it against lateral motion. The axle is positively held in location, so there is no "knock-back" of the rear brake pads and caliper pistons. When your car has 315mm of sticky Falken Azenis RT615K+ tires trying to pull the axles out as it corners, you will need the added strength too.

The Body

The Wilwood Workhorse was a Southern California car all its life, but that doesn't mean it was clean and rust free. Years of unsympathetic owners and inattentive parking lot neighbors had left innumerable scratches, dings, and rust spots in our poor pony. Luckily, the early Ford Mustang has some of the best restoration support of any car made in the last 100 years.

All of the front sheet metal is available and easily replaced, but we decided to take some weight off and use composite parts instead of steel. Maier Racing has been making fiberglass parts for Mustangs almost since there have been Mustangs. We used nearly everything they had for the front of the car, including the Shelby style hood, flared fenders, chin spoiler, and front racing apron with opening for an oil cooler. This should take some weight off the front of the car, and let it breath and cool better.

In the back, we did use real steel from National Parts Depot. We chose to weld in new rear fenders and reskin the doors instead of trying to straighten and remove the rust from the original parts. We also chose Maier Racing's rear trunk lid with built in spoiler, and rear fender flares to complete the look and cover our huge tires.

Interior

The interior of the car is going to be a mix of race safety and support, and over the road comfort. We started by welding in new floorboards to replace the rested originals. While we were at it, we cut the seat risers out and welded them in two inches lower, so a helmeted driver would have more room especially with the added roll bar. In the back, we cut out the original wheel tubs, and welded in 2-inch wider mini wheel tubs from Chassisworks to allow wide rear tires without huge flares.

Chris Alston's Chassisworks bent and cut a roll cage for the car for safety, but with a minimum of inconvenience for street use. There are the expected four uprights around the passenger compartment, with diagonals tying into the rear suspension, but there is only one "door bar" and it is very low for ease of entry. While we had the whole car apart, we also tied the front suspension to the roll cage through the firewall. Not only does a roll cage contribute to crash and rollover safety, but it brings our 1960s Mustang up to 21st-century torsional rigidity.

A pair of Corbeau sport seats were installed on the lowered risers, with useful bolsters, but the ability to recline and slide like a factory seat. The Corbeau seats have proper provisions for the five point camlock harnesses from Impact Racing, which will hold you in place against some serious G-forces.

The steering wheel is attached to a Ididit steering column, held in place by our custom machined mount. Because we plan on driving the Hot Rod Power Tour and other events, as well as cruising in Southern California, we added air conditioning from Vintage Air as well.

Under the Hood

Wilwood is all about the brakes, but we wanted this car to have enough power to really need the good stuff, and we wanted it to start and run without any tinkering no matter the weather. We settled on a Ford Performance 5.0-liter 32-valve DOHC Coyote crate motor rated at 460hp, which ought to be plenty in a car that weighs about 3,000lbs.

The majority of cooling is taken care of by an aluminum radiator by C & R Racing specifically designed for the Coyote motor in early Mustangs. It comes with electric fans and shroud, for a foolproof fit. The second time we took the drivetrain out, we hit on the idea to machine a billet aluminum core support that we can unbolt easily for engine removal.

Headers from Doug's Headers were specially designed using this car as the template, and are now a production item for anyone swapping a Coyote into an early Mustang. Fuel gets to the engine from the custom Rick's Tanks stainless tank with Aeromotive fuel rails, regulator, filter, and plumbing. To keep oil pressure in the motor no matter how hard the car corners, a Canton Accusump oil accumulator was plumbed into the system, which prevents oil starvation, and a Setrab cooler keeps it cool.

The transmission is a six-speed manual from Tremec, a Magnum T-56 for great acceleration and relaxed cruising on the freeway. A Centerforce DYAD DS dual-disc clutch handles launch after launch without compliant. Of course, the clutch is controlled by a Wilwood master and slave cylinder, with Wilwood pedals. A matching brake pedal, with dual compact remote reservoir master cylinders and adjustable balance bar joins it on the fire wall.

Wheels, Tires and Brakes

The classic shape of the Mustang might look better with a classic five-spoke wheel, or Minilites, but we wanted an open design and a dark finish to show off the brakes. The wheels we used are the Pro Lite style by Boze Alloys, in an 18-inch diameter by 9.5-inch width in the front, and 18-inch by 11-inch in the rear.

The tires are the Falken Azenis RT615K+ maximum performance summer tire, with a 200 treadwear rating. These sticky tires give almost race tire levels of performance, but will still last thousands of miles on the street. The front tires measure 275/35R18, while the rear 315/30R18 tires are wide enough to roll flat newly poured pavement.

As a development car, the Workhorse has worn a lot of different brakes and rotors over the years, not all of which were standard production pieces. Currently, there are a pair of Aero6 radial mount six-piston calipers on the front, which were custom fitted to the TCI spindles. In the back are the latest generation of forged billet Superlite internal four-piston calipers. Our Spec37 iron rotors with directional venting mount to our flared aluminum hats, and turn on Wilwood's billet front hub. The rear uses nearly the same rotor set up, but with our internal drum parking brake mounted inside the rotor hat.

We take the Workhorse Mustang out whenever we get a chance to stretch its legs. Can you blame us? If you see the Wilwood crew at an even, like the NMCA West autocross events, stop over and say hello. We love to talk to people who use our brakes, or answer questions about our setup.

Parts Sources:

• Ford Performance 5.0-liter Coyote V8 engine
• Tremec T-56 Magnum 6-speed manual transmission
• Total Cost Involved Pro Touring tubular control arm and coil over front suspension
• Total Cost Involved Torque arm rear suspension and subframe connectors
• Chris Alston Chassisworks 2-inch wider rear wheel tubs for 315mm tires
• Strange Pro Touring full floating aluminum Ford 9” rear differential
• Falken Azenis RT615K+ tires 275mm front, 315mm rear
• Centerforce DYAD DS clutch
• Corbeau bolstered sport seats
• Impact Safety 5-point race harnesses
• Chris Alston Chassisworks 6-point roll cage with front sub-frame tie in
• Ididit steering column
• Vintage Air air conditioning
• Maier Racing front fiberglass fenders, hood and trunk
• National Parts Depot replacement doors and quarter panels
• Boze Alloy Prolite Wheels 18” x 9.5” front, 18” x 11” rear
• Doug’s Headers Coyote swap Mustang headers
• Rick’s Stainless Vaporworks fuel tank
• Aeromotive fuel rails, filter, regulator, and plumbing
• Canton Accusump oil pressure accumulator
• Setrab oil cooler
• Russel braided stainless hoses and fittings
• C and R Radiators early Mustang Coyote swap radiator with fans
• NRG Steering Wheel

And of course...

• Wilwood disc brakes front and rear

But Wait, There's More ...

A visit from the popular YouTube enthusiast channel AutotopiaLA, captured the Workhorse going through its paces.

The Workhorse loves to do autocross as well. Watch Mike Hamrick putting both pedals down at an NMCA West Autocross event. If you haven't been to one of these events you don't know what you're missing!

To see videos of the Workhorse Mustang project during development phases watch the series in this playlist.

Click to download a 2-page flyer all about the Workhorse: